Whilst its a great app, the business logic is massively flawed.
Lets say for arguments sake that they still have the 100,000 'tokens' that they had a while ago.
That works out at a maximum income (taking Apple's 30% cut into account) of $1.4 million.
Obviously they are a fairly small company, however when that runs out (and remember, I didn't take into account any expenses, so the actual profit will be significantly lower) they are promising to keep developing the software, despite having no income.
Whilst some of their other products may subsidise the ongoing development, when it comes to major updates, they have zero incentive once they know that they cant make a penny off of it, even if they release 'v2' and charge all over again, as they wont be issued more tokens for it.